Drug interactions
Isocarboxazid + Phenobarbital
Severity: Major
Isocarboxazid and Phenobarbital: major interaction.
Last updated Sources: UK SmPC
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
MAOIs can potentiate the sedative effects of barbiturates, producing excessive CNS depression. Hypotension and respiratory depression may also be more pronounced.
What this interaction means in plain words
Isocarboxazid and Phenobarbital can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Why it happens
Additive CNS depression, and MAOIs may inhibit the metabolism of barbiturates.
What to do
Avoid combining where possible and use an alternative anticonvulsant or sedative. If phenobarbital is needed, start at a reduced dose and monitor sedation, respiration and blood pressure.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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References
Other interactions of Isocarboxazid
- 5-HTP + Isocarboxazid Contraindicated
- Amitriptyline + Isocarboxazid Contraindicated
- Amobarbital + Isocarboxazid Contraindicated
- Amoxapine + Isocarboxazid Contraindicated
- Apraclonidine + Isocarboxazid Contraindicated
- Atomoxetine + Isocarboxazid Contraindicated
Frequently asked questions
Can I take Isocarboxazid with Phenobarbital?
MediHelp rates the interaction as major. Isocarboxazid and Phenobarbital can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. MAOIs can potentiate the sedative effects of barbiturates, producing excessive CNS depression. Hypotension and respiratory depression may also be more pronounced.
How serious is the interaction between Isocarboxazid and Phenobarbital?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid combining where possible and use an alternative anticonvulsant or sedative. If phenobarbital is needed, start at a reduced dose and monitor sedation, respiration and blood pressure.
What other medicines interact with Isocarboxazid?
MediHelp also lists interactions of Isocarboxazid with, for example, 5-HTP, Amitriptyline, Amobarbital. The full list is on the Isocarboxazid page.
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